Modulating high pressure air valve



Dec. 24, 1957 w. p. ANTRIM, R" 2,817,362 MODULATING HIGH PRESSURE AIR VALVE Filed Feb. 1, 1954 INVENTOR. WILLIAM D. ANTRIM JR.

United States atent Ofilice 2,817,362 Patented Dec. 24, 19 57 2,817,362 MODULATING HIGH PRESSURE AIR VALVE William D. Antrim, Jr., Paramus, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application February 1, 1954, Serial No. 407,309

6 Claims. (Cl. 138-46) This invention pertains to new and useful improvements in air valves. It is particularly concerned with a modulating air control valve useful in modulating air from a source of decreasing relatively high pressure to a constant lower pressure. The device finds particular use in supplying air at a constant pressure to the fuel-air combustion chamber of a jet engine starter.

It is essential that the air supply to the combustion chamber of a jet engine starter be in a proper and constant ratio to the fuel supply with which it mixes. To this end, a proper air control flow valve is essential. It is desirable that such valve occupy a minimum of space and that it function to allow a steady mass rate of pressure air flow to the combustion chamber to a minimum of depletion of an unreplenished high pressure air source. It is highly desirable, however, that the response of such valve be immediate, without fluctuation, and that it operate without danger of damage to the cooperating parts.

A feature of the valve of the present invention lies in its,

novel construction and smooth operation, as well as in the manner in which it is operated so as to pass a constant modulated flow of pressure air from a source of decreasing high pressure to the combustion chamber until the high pressure air supply has been substantially depleted.

A further feature of the invention is found in the relative association of the valve parts whereby the latter are cushioned by air against fluctuation and damage while operating.

Another feature of the invention which materially adds to the efliciency and long life of the device is provided by the novel construction of the valve head and its association with the valve opening. The valve is supported for sliding movement so as to operate to constrict the valve opening Without limiting against any valve seat. Through this construction the possibility of damage to the valve in seating and consequent inefiicient operation of the valve is eliminated.

An object of the invention is, therefore, an improved type of air control valve for the purposes stated.

Another object of the invention is to provide a modulating pressure air control valve having a seatless valve head.

Another object of the invention is a modulating air control valve that will maintain a constant rate of output flow from a depleting high pressure air source until substantial depletion of the source.

A still further object of the invention is an improved type of control valve that finds particular use with the combustion chamber of a jet engine starter.

The invention further lies in the general construction of the device, as well as in the particular arrangement and cooperative organization of its various elements.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawing wherein an embodiment of the invention is illustrated. It is to be expressly understood, however, that the drawing is for purposes of illustration and description, and is not to be construed as defining the limits of the invention.

The drawing is a cross-section view of an air control valve embodying the invention.

In describing the invention in detail, reference is directed to the drawing, wherein there is disclosed a housing 1 having an elongated bore 2 therethrough. The latter is sealed at the bottom by a cap 3, and includes a high pressure chamber 4 and a low pressure chamber 5 above it. Chamber 4 is provided with an intake port 7 suitably adapted for connection with a limited source of high pressure air. Chambers 4 and 5 communicate with one another through a valve mechanism 8 contained in a part of the bore between the two chambers. The low pressure chamber 5, also called the outlet chamber, is pro-, vided with a nozzled port 9 in its side for communication with a fuel-air combustion chamber 11 of a jet engine starter.

The valve mechanism is characterized by a cylindrical valve head 12 and an annular valve opening 14 through which it slides. A feature of the valve is that it does not seat, but instead, slides through a modulating constriction and at most nearly closes the opening. To this end, there is provided a pair of annular elements, one of which designated 15 serves as a guide and support for the valve head and the other of which 16 serves as a means cooperating with the valve head to constrict the valve opening.

Guide element 15 closes over the top of chamber 4. It includes a short upwardly extending skirt wall 17 which lines the housing. Stepped in from the lower end of the skirt by a shoulder 18 is a depending crown portion 19. A recess 21 formed on the inside of the crown is of a diameter to receive the cylindrical wall 22 of the valve head in sliding contact therewith and is of a depth sufiicient to receive substantially the whole of the valve head. A snap ring 23 received in a groove of the housing immediately below shoulder 18 holds guide piece 15 in place.

Element 16, represented as a thickened ring, is retained immediately above skirt 17 of element 15 by means of an outer rib 24 which rests at one side on the end wall of skirt 17 and limits at the other side against a shoulder 25 of the housing. The space formed between shoulder 18 and the ring 16 represents the valve opening. The valve opening communicates with the high pressure chamber 4 below through ports 27 in shoulder 18. The opening through ring element 16 is concentric with the valve head 12, though of a slightly larger diameter, so that the valve head would if moved upwards pass through the ring without contacting the innermost wall of the latter.

Valve head 12 is integral with and axially carried at the lower end of an elongated shaft 28. The latter extends axially up through the low pressure chamber. Axially bolted at 29 to the opposite end of the shaft is a piston head 31 of large area. It is adapted to slide in a piston cylinder 32 fitted in the top end of the housing bore. The upper end of the low pressure chamber is enlarged to accommodate the sliding movements of the large piston head.

The piston cylinder includes a head 33 of thickened proportions which closes over the top of the bore 2 and is provided with a depending cylindrical skirt 34 which lines the bore and is supported at its end by a shoulder 35 provided by the enlarged upper part of the housing bore. A snap ring 36 fitted into a groove of the housing immediately above the cylinder head holds the latter in place. The piston disc is constantly tensioned upwards by a coil spring 37, one end of which is contained in a recess of the piston disc and the other end of which is retained in the crown 38 of a cup plate 30. The cup plate is supported by an annular flange 26 upon the shoulder 35.

A pressure equalizing passage 39 through the housing communicates the low pressure chamber with the portion thereof above the cup plate.

When the piston disc is tensioned to its uppermost position, the upper surface 41 thereof, which. is flat, limits flush against a flat complementary undersurface of the cylinder head, and the bolted. end 29 of shaft 28 is freely received with space to spare in a recess 42 in the cylinder head.

Recess 42 communicates through a cylinder head bore 40 and a housing passage 43 with the output of a conventional pressure air reducingdevice 44. The intake of the latter connects at 45 with. the high. compression chamber 4. v

When the piston disc is tensioned to its normal uppermost position, valve head 12 is drawn toits nearly closed position. The valve head never fully closes. In this nearly closed position the foremost part of the valves outer wall is positionedwith slight clearance from. the adjacent inner-. most part of the wall of the ring element 1-6 so as to provide a constricted opening. The inner wall of thelatter ring is beveled downward and outward as at 46 so that very slight downward movement of the valve head will open the constriction wider. The constriction opens progressively wider as the valve head moves downward. in thisnearly most closed position, the lower portion. of the valve wall 22 is in contact with and is supported by the adjacent wall of recess 21. a Opposite ends of the valve head are recessed at 47,. and a passage 48' through the head communicates the one with the other.

In operation, high pressure air from a limited source enters through port 7 to chamber 4. It flows from here through the pressure reducing device 44 to'the recess. 42 above the piston disc at a relatively reduced pressure. It also flows through the constricted valve opening 14- to the low pressure chamber 5.

The fiow to the reducing device is reduced therein to a desired steady pressure which acts upon the piston head to force valve head 12 down. This lessens the constriction of the valve opening and allows an increased flow from the pressure chamber 4 to the low pressure chamber 5. The flow from the low pressure chamber passes through the nozzled port 9 to the combustion chamber 11. It also passes through the equalizer passage 39 to equalize the pressure on both sides of the spring retaining plate 30, and it also flows through the valve head passage 48 to balance pressures at both ends of the valve head.

The pilot pressure to the recess 42 is relatively less than that received in the high compression chamber and is steadied sothat the differential pressure across the tensioned large area piston disc opens the valve constriction as needed to provide a modulated constant output pressure to the combustion chamber.

The output flow to the combustion chamber continues at a steady rate until substantial depletion of the main supply source.

A particular advantage of the device is found in the novel arrangement of the valve head with respect to the valve opening, whereby the valve does not seat but merely constricts the valve opening. This avoids chopping and damage to the valve head due to any vibration that might be placed upon it, and which damage would otherwise occur were the valve to engage upon or limit against a seat. Further, the valve head is at all times supported by the wall of the guide piece recess 21 at one end and is supported by the thickened piston disc at the opposite end of the shaft. This structure reduces the possibility of fluctuation to a minimum. It can further be seen by the particular structure of the valve mechanism how all its moving parts are cushioned and supportedduring operation, whereby abrupt movements of the. valve parts are prevented and the general operation of the valve issmooth. In moving to its normal position, the flat upper surface ofthe piston head is cushioned by air above it until it 4 abuts flat against the cylinder head. A bleeder hole 49 prevents an air block from forming above the piston head.

Although but one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention, as the same will now be understood by those skilled in the art.

What is claimed is:

1. In a modulating air-control valve of the character described including a housing having a high pressure air intake chamber and a low pressure output chamber axially aligned with one another, a pair of spaced elements providing an annular valve opening by the space between them communicating the chambers with one another, an elongated cylindrical valve head, one of the spaced elements forming a cup member continuously sleeving an end portion of the valve head for reciprocable movement therein, and the other spaced element comprising a thickened ring having an opening concentric with the cylindrical valve head and having a diameter slightly greater than the valve head, means for tensioning the valve across the annular valve opening into close proximity with the inner Wall of the ring element to provide a constricted opening communicating one chamber with the other, and air pressure operated means for moving the valve head against the tensioning means away from the inner wall of the ring element.

2. In a valve as in claim 1, wherein the air pressure operated means comprises a large piston head movable in the low pressure chamber and an elongated shaft axially secured at one end to the piston head and at the other to the valve head, a retaining plate positioned across the low pressure chamber below the piston head and having an axial hole through which the shaft passes, and wherein the tensioning means comprises a coil spring surrounding the shaft and limited between the retaining plate and the underside of the piston head.

3. In a modulatingair-control valve of the character and use set forth including-a housing having a high-pressure air intake chamber and a low pressure output chamber axially aligned with one another, a pair of spaced elements intermediately of the two chambers and forming an annular opening communicating the one chamber with the other, a cylindrical elongated valve head, one of the spaced elements including a guide cup continuously supporting the lower end of the valve head in sliding contact therewith and the other spaced element comprising a ring having anopening concentric with the cylindrical valve head .and of a diameter slightly greater than the valve head, a piston head reciprocable in the low pressure chamber, an elongated shaft extending axially from one end of the low pressure chamber to the other, the shaft carrying axially at the lower end thereof the valve head and at the upper end thereof the piston head, a coil spring surrounding the shaft and constantly urging the elongated shaft upwards so as to bring the upper end of the valve head in close proximity to the inner wall of the ring element to constrlct the annular opening, and air pressure means communicable with the upper side of the piston head for moving the shaft downwards so as to carry the valve head away from the constricted opening.

4. A modulating air-control valve of the character described including a cylindrical valve head, an annulus having a beveled opening which is progressively flared from a circular outlet edge having a diameter slightly larger than said cylindrical valve head, means connected to said valve head constructed to reciprocate the cylindrical valve head axially within the opening to constrict the same Without the head at'any time contacting the inner wall of the annulus, and a stationary cup member in opposedaxial spaced relation to the annulus continuously supporting therein an end of the valve head as the latter is reciprocated.

5. In a valve of the character described including a housing having a high pressure air inlet chamber formed in opposed spaced relation to a low pressure outlet chamher and further having a passageway connecting the one chamber with the other: a thickened annulus fitted into the passageway providing a conical opening axially communicating one chamber with the other, wherein said annulus the wider diameter of the opening opens out into the high pressure chamber and the narrower diameter of the opening is located near the opposite end thereof and flares out into the low pressure chamber; an elongated cylindrical valve head axially reciproca-ble in the conical opening to progressively constrict the same as the valve head is progressively moved toward the narrower diameter end of the opening, the valve head having a diameter slightly less than that of the narrower diameter of the conical opening; an elongated valve stem extending through the low pressure chamber into the conical opening, said valve stem having a piston at one end and axially connecting the piston at one end with the valve head at the other for reciprocating the valve head in the conical opening; a fixed cup member in the high pres sure chamber located in opposed spaced axial relation to the conical opening, the cup member opening out in the direction of the conical opening and continuously sleeving and supporting an end portion of the elongated valve head for sliding movement in the cup; and the valve head further characterized by a recess in opposite ends thereof to form a relatively thin partition wall in between the recessed ends, and the latter wall having an opening providing a passage communicating the recesses with one another, whereby an air block is prevented from forming in the cup in the reciprocation of the valve head, and balancing air pressures are enabled against opposite ends of the valve head.

6. A modulating air-control valve of the character described including a cylindrical valve head of uniform diameter, an annulus having a beveled opening which is progressively flared from a circular outlet edge having a diameter slightly larger than said cylindrical valve head to a large-diameter inlet, said valve head arranged axially in said opening and having one end within said opening and adjacent said circular outlet edge, said valve head having its other end projecting axially from said inlet of said opening, means connected to said valve head constructed to reciprocate axially the cylindrical valve head from adjacent said circular edge to beyond said inlet so that said opening is opened and constricted without the head at any time contacting the surface of the opening, and a stationary cup member axially spaced from said annulus and continuously supporting therein said other end of the valve head as the latter is reciprocated.

References Cited in the file of this patent UNITED STATES PATENTS 2,277,162 Soderberg Mar. 24, 1942 2,333,775 Gille Nov. 9, 1943 2,523,826 Heinzelman Sept. 26, 1950 FOREIGN PATENTS 270,017 Great Britain May 5, 1927 595,243 Germany Apr. 5, 1934 

